Internal winding spool



FIG. 1 is a perspective view showing my new design;

FIG. 2 is a left hand end view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a front thereof; and,

FIG. 6 is a back view thereof.

The broken lines represent portions of the structure that form no part of the claim. 

CLAIM I, claim the ornamental design for an internal winding spool, as shown and described. 